Insulated conductor



E. B. WHEELER INSULATED CONDUCTOR Oct. 16, 1928. 7

Filed March 27, 1924 Patented Oct. 16, 1928.

UNITED STATES 1,687,912 PATENT OFFICE.

EDMUND B. WHEELER, on EW YORK, N. Y.', ASSIGNOR TO wEs'rEnn ELEc'rRIo 00M PANY, INCORPORATED, on NEW YORK, N. Y., A conronn'rron on NEW YORK.

INSULATED CONDUCTOR.

Application filed March 27, 1924. Serial No. 702,176.

This inventiomrelates to insulated con-' ductors. Y

An object of the invention is toprovide an insulation for conductors which occupies a small amountof space and which has satisfactory dielectric properties together with exceptional continuity and imperviou'sness.

Baked enamels, while having many desirable qualities as insulators for. electrical conductors, are exceedingly thin, and therefore often contain pin holes or like i-mper-' fections, and also in certain cases fail to provide the'necessal y dielectric between associated conductors.

In accordance with the general features of this invention, there is provided a .con-' ductor having a coating of enamel whichis surrounded by a layer of vulcanized rubber.

In case a plurality of conductors are to be used together, all, except one of the conductors may be coatc'el with enamel only and may be spiralled about a central conductor which may becoated both with enamel and with rubber. The' rubber layer upon this conductor may be made sufficiently thick so that there will be the necessary dielectric between it and the other conductors. 'It more than one enamel coated conductor is used, these conductors should be so spaced that they are not in mechanical contact.

The various features and objects of the invention will appear more fully from the following detailed description taken in con-- nection with the accompanying drawings.

Fig. 1 shows a conductor insulated in-accordance with this invention. I p Fig. 2 shows such a conductor with an enameled conductor spiralled about it.

Fig. 3 shows the conductor of Fig.1 with two enameled conductors spiralled about-it. In Fig.1 the conductor 1 is covered with an enamel coating 5 surrounded with a covering of vulcanized rubber 6. Such an insulation is readily'tormed when anenamel which can withstand, the usual vulcanizing temperature of rubber is used, and when the .heat is carefully controlled during the vul'canizing.-- A self-vulcanizingrubber compound may also be used. \Veak spots I in the layers 5 and 6 tend to,be staggeredand therefore the layer of rubber covers any holes in j the enamel, so that there is produced an exceedingly continuous and im- .pervious insulation. In order to protect the insulation from wearer mechanical injury,

it may be covered with a protective-braidin -7. Such braidings are often impregnated 'June 23", 1914. This patent also discloses a suiable manner of applying the enamel to the wire. Several suitable rubber insulations are known to the trade, which vulcanize at temperatures well below the baking temperature of that enamel.

A conductor such as shown in Fig. 1 is superior to a conductor insulated only with rubber, both because of its excellent electrical properties and because it occupies less space and is cheaper to produce, inasmuch as only a thin layer of rubber is re uired. For example, a conductor insulate with enamel and thencovered with a layer of rubber thick is superior for many purposes to a conductor insulated only with rubber'when the rubber layer is thick.

Fig. 2 shows two spiralled insulated conductors 10 and 11. Conductor 10 is insulated with an enamel coating 12 while conductor 11 is insulated with an enamel coating 13 andthen covered by a vulcanized rubber layer 14 of suflicient thickness so that conductors 1-8 and 19 which are coated with enamel 20 are spiralled about theinsulated conductor 15. The assembly, which will be practically cylindrical in form, may be enclosed in a protective braiding 9. Three or more enamelled conductors may, of course,

be spiralled about the insulated conductor 15 provided that they be spaced so that the electrical-demands (such as insulation resistance, capacity, and conductance) of the system as a Wholemay be met. -Thus,- a number of conductors may be associated with each other 'in an exceedingly small space without sacrificing, those electrical properties which it is desired to maintain.

ents ofsaid rubber and the said rubberv alone being too thin to afiorcl sufiicient resistance to moisture but thick enough in combination With said enamel to produce a satisfactory flexibility. v

In Witness whereof, I hereunto subscribe my name this 24th day'of March, A. D.

EDMUND B. WHEELER.

insulation of great thinness and 

